Millions of people in Iran could be displaced by what the United Nations is calling the country's worst drought for 30 years.

UN officials fear that water shortages could lead to mass migration of rural populations into Iran's overcrowded cities, where water is already in short supply.

In a report, officials say the drought - now in its second year - is affecting more than half of Iran's population of 60 million people.

They also warn the crisis is likely to worsen in the next few months, as no rain is expected until November.

'Extreme strain'

According to the report, the crisis has "placed an extreme strain on water resources, livestock and agriculture, leading to greater hardship and human suffering".

Drought in Iran

18 out of 28 provinces affected

2.8 million tonnes of wheat destroyed

800,000 animals dead from malnutrition

70% of rural water supplies disrupted

The drought has destroyed crops and decimated livestock numbers, and Iran has been forced to import additional food supplies.

The water supply to many areas has been disrupted as parched lakes and reservoirs dry up completely.

"I have seen droughts that left a shortage for agriculture, but I have never before seen people themselves simply running out of water," said Rod Kennard, of the UN's Food and Agriculture Organisation.

Contingency plan

The FAO is attempting to draw up a plan to help local authorities draft contingency measures to cope with the crisis.

Its report praises the measures already taken by the Iranian Government, but says the situation is fast becoming critical.

It warns that Iran's situation could be worsened by an influx of people fleeing similar conditions in Afghanistan in search of water and pasture.

Regional problem

Water shortages - compounded by abnormally high temperatures this year - have been ravaging many other Middle Eastern nations, including, in particular, Iraq and Jordan.

The drought has also caused an ambitious multi-million dollar project to supply water from Iran to Kuwait to be shelved.

A British-Iranian-Kuwaiti consortium had proposed building a 300-kilometre (192-mile) pipeline under the Gulf to send water to the emirate from Iran's Karkheh river.

But according to Iranian press reports, the plan has now been postponed indefinitely.